You know that in modern time (relatively speaking, it is only a short time since) the tomato has been introduced as a kind of staple food. Many people are fond of it. Now the tomato is one of the most interesting subjects of study. Much can be learned from the production and consumption of tomatoes.
Those who concern themselves a little with these things — and there are such men to-day — rightly consider that the consumption of the tomato by man is of great significance. (And it can well be extended to the animal; it would be quite possible to accustom animals to tomatoes). It is, in fact, of great significance for all that in the body, which — while within the organism — tends to fall out of the organism, i.e. for that which assumes — once more, within the organism — an organization of its own.
Two things follow from this. First, it confirms the statement of an American to the effect that a diet of tomatoes will, under given conditions, have a most beneficial effect on a morbid inclination of the liver. In effect, the liver of all organs, works with the greatest relative independence in the human body. Therefore, quite generally speaking, liver diseases — those that are rather diseases of the animal liver — can be combated by means of the tomato.
At this point we can begin to look right into the connection between plant and animal. I may say, in parenthesis, suppose a person is suffering from carcinoma. Carcinoma, from the very outset, makes a certain region independent within the human or animal organism. Hence a carcinoma patient should at once be forbidden to eat tomatoes. Now let us ask ourselves: What is it due to? Why does the tomato work especially on that which is independent within the organism — that which specializes itself out of the organic totality? This is connected with what the tomato needs for its own origin and growth.
The tomato feels happiest if it receives manure as far as possible in the original form in which it was excreted or otherwise separated out of the animal or other organism — manure which has not had much time to get assimilated in Nature — wild manure, so to speak. Take any kind of refuse and throw it together as a disorderly manure- or compost-heap, containing as much as possible in the form in which it just arose — nohow prepared or worked upon. Plant them there, and you will soon see that you get the finest tomatoes. Nay, more, if you use a heap of compost made of the tomato-plant itself — stem, foliage and all — if you let the tomato grow on its own dung, so to speak, it will develop splendidly.
The tomato does not want to go out of itself; it does not want to depart from the realm of strong vitality. It wants to remain therein. It is the most uncompanionable creature in the whole plant-kingdom. It does not want to get anything from outside. Above all, it rejects any manure that has already undergone an inner process. It will not have it. The tomato's power to influence any independent organization within the human or animal organism is connected with this, its property.
To some extent, in this respect, the potato is akin to the tomato. The potato, too, works in a highly independent way, and in this sense: it passes easily right through the digestive process, penetrates into the brain, and makes the brain independent — independent even of the influence of the remaining organs of the body. Indeed, the exaggerated use of potatoes is one of the factors that have made men and animals materialistic since the introduction of potato cultivation into Europe. We should only eat just enough potatoes to stimulate our brain and head-nature. The eating of potatoes, above all, should not be overdone.
Agriculture , Rudolf Steiner, Lecture 8